Application servers provide an environment for programmers to write application programs that perform services. Application servers typically include resources provided by third party vendors that can be called by application programs. Application servers may implement large numbers of the resource objects for application program use. One such application server is Web Logic Server (WLS) of BEA Systems of San Jose, Calif.
Application servers implement a resource pool to manage and track resource status. Typically, different subsystems like JDBC, Connector and JMS subsystems use separate resource pooling code implementations. Each implementation generally performs the same function for the corresponding system.
A resource adapter is a segment of code that represents an Enterprise Information System (EIS). More specifically, a resource adaptor is a system-level software driver used by an application server, such as WebLogic Server, to connect to an enterprise information system (EIS). A resource adapter serves as the “J2EE connector.” The connector architecture implementation supports resource adapters developed by EIS vendors and third-party application developers that can be deployed in any application server supporting the Sun Microsystems J2EE Platform Specification, Version 1.3. Resource adapters contain the Java, and if necessary, the native components required to interact with the EIS.